Sales of The Beatles: Rock Band have exceeded expectations, Viacom said on Wednesday, even as the first sales figures since the video game launched last week indicated that Activision’s rival Guitar Hero 5 game appeared to have the edge in the battle of the bands.

“It’s been terrific,” said Philippe Dauman, chief executive of Viacom, which owns MTV Games and Rock Band developer Harmonix. “Sales have exceeded our internal projections and we’ve sold 25 per cent of our inventory in the first week,” he told a Goldman Sachs media conference in New York.